The PARTNERSHIPS Act is a tax reform bill that targets what lawmakers see as unfair tax advantages used by certain business partnerships. The main focus is on preventing wealthy owners from using complex partnership structures to avoid paying their fair share of taxes.

The bill creates new rules for how profits and losses are divided among partners in large partnerships controlled by related business entities. Instead of allowing flexible profit-sharing arrangements that can favor certain partners, the law requires these partnerships to use a "consistent percentage method" where each partner's share of profits matches their actual financial investment in the partnership. This prevents situations where partners with smaller investments receive disproportionately large profits or tax benefits.

The bill also closes several other tax loopholes commonly used in partnership arrangements. It eliminates special rules that allowed partners to avoid taxes when receiving distributions, changes how gains from contributed property are taxed, and adds new requirements for partnerships to report their structure to the IRS. Additionally, it applies the net investment income tax (a 3.8% tax on investment gains for high earners) to business income earned through partnerships, ensuring wealthy individuals can't use partnership structures to escape this tax.

Overall, the PARTNERSHIPS Act aims to make partnership taxation fairer and more transparent by preventing sophisticated tax avoidance strategies while ensuring that partners pay taxes based on their actual economic stake in the business.